1. Field of the Invention
The invention relates to a valve plate for a sliding gate valve at the outlet of a vessel containing molten metal. The invention includes a refractory plate, a metal shell surrounding the refractory plate, and centering means which is so constructed that the valve plate may be inserted loosely in a metal frame of the sliding gate valve and centered therein, at least in a direction of movement. The invention also relates to a sliding gate valve for the valve plate.
2. Description of the Related Art
A mentioned refractory valve plate according to GB-A-2 213 412 has a centering means, which is shaped as a cylindrical surface formed by a metal can or a bandage concentrically arranged around a flow through. This cylindrical surface is formed to radiate outward and is machined so that the plate can be engaged with substantially no free play within a metal frame. With this kind of centering, it is necessary that such an outward surface is provided. As a result, the shape of the plate can be only altered in a limited fashion.
In a known sliding nozzle plate disclosed in the publication DE-A-44 33 356, a metal housing, which surrounds a plate from below and laterally, has one or a number of projections which fit into corresponding recesses in the metal frame. In the inserted state of the plate, its projections are retained with a lateral clearance in the range between 0.1 and 1 mm in a direction of movement of the plate. These projections must, therefore, be provided with a very narrow tolerance and are correspondingly expensive to produce.
Against this background, it is an object of the present invention to provide a valve plate of the type mentioned above which, with precise centering in a metal frame, may be manufactured simply and economically. This valve plate is also to be so dimensioned that the space requirement when such plates are stacked is thereby maintained at a minimum and the risk of damage to this centering means or a centering device can be eliminated to the greatest extent possible.
This object is solved in accordance with the invention if the centering means or centering device is constituted by preferably two abutment surfaces arranged at a defined spacing from one another which rise up substantially, at least partially, vertically towards a plate support afforded by a metal shell and having a thickness approximately the same as the metal shell thickness. These abutment surfaces being so arranged that, in the inserted and centered state of the plate, they engage correspondingly shaped abutment surfaces on the metal frame.
This valve plate may be manufactured simply with its construction in accordance with the invention and such a centering in a metal frame of the sliding gate valve is, however, nevertheless ensured with it, such that it can be used in an extremely operationally secure manner.